Fireproof smoke damper

ABSTRACT

A fireproof smoke damper having a casing or duct which includes a curved sector and a shutter plate within the sector and pivoted at the center of curvature thereof.

United States Patent 1191 Iwata Oct. 14, 1975 [54] FIREPROOF SMOKEDAMPER 2,226,815 12 1940 Haines 236/49 2,251,822 8/1941 Car1son....126/293 [75] Inventor: Yosluaki lwata, Fu rsawa, Japan 3,010,451 11/1961Hodgins 26/285 B [73] Assigneez .Nittan Company, Limited, Tokyo3,172,347 3/1965 1011115011 98/1 Japan 3,227,219 1/1966 Boyer et a1.169/5 3,275,286 9/1966 Wood 251/30 [22] Filed: Mar. 15, 1974 3,303,8862/1967 Tattersall et a1 169/5 3,352,159 11/1967 Bruce et a1. 251/299 pp451,343 3,719,321 3/1973 McNabney 236/49 3,730,] 12 5/1973 Hutchinson eta1 98/59 52 us. c1 251/299; 126/285 R; 236/49; 2x33; 22%;?

126/293;l69/5;169/60 51 1111. cm. F16K 1/16; F23L 13/00; A62C 37/18FOREIGN PATENTS 0R APPLICAUONS [58] Field of Search 98/1, 58-62,1,017,761 10/1957 Germany 126/285 98/108; 126/285 R, 285 B, 287.5, 293,418,982 3/1947 Italy 169/5 285.5, 292, 297, 289; 251/30, 299, 298, 303,

300; 236/49; 169/60, 61, 65, 5 Primary ExaminerWil1iam E. WaynerAssistant Examiner-Henry C. Yuen [56] References Cited Attorney, Agent,or FirmEugene E. Geoffrey UNITED STATES PATENTS 422,956 3/1890 Malmborg126/285 B [57] ABSTRACT 472,461 4/1892 Lundstedt.... 126/285 B Afireproof smoke damper having a casing or duct 521,531 6/ 89 st r126/293 which includes a curved sector and a shutter plate 1,515,234 11/1924 236/49 X within the sector and pivoted at the center of curva-1,647,036 10 1927 Dileo 251/298 we thereofi 2,112,554 3/1938 Beam126/287.5 2,224,705 12/1940 Stringer 126/285 B 4 Claims, 2 DrawingFigures US. Patent Oct. 14, 1975 .1 III! F. l-lll.

FIREPROOF SMOKE DAMPER This invention relates to a fireproof smokedamper for use in the ventilation system of a building.

When a fire breaks out in a room ofa building, smoke and flame producedby the fire are transferred to other rooms and to the outside of thebuilding through exhaust ducts of the ventilation system. This not onlyobstructs fire-fighting and sheltering action but also promotes thespread of fire. Many types of dampers have been used with a ventilationduct but the prior dampers have commonly employed a butterfly typeshutter plate rotatably supported on a shaft in a straight tubulardamper casing. Such types of prior damages have gaps between the shutterplates and the casings for the purpose of preventing interference withthe operation of the damper due to rusting of the rotating portion andcontamination with dust. As a result, sufficient interception of smokeand flame'cannot be obtained because the closed damper is not air-tight.

Accordingly, an object of this invention is to provide a novel andimproved fireproof smoke damper which overcomes the abovementioneddisadvantages of the prior dampers and will effectively prevent thepassage of smoke and flame into ventilation and other ducts.

The'damper according to this invention includes a damper casing having alongitudinal section at least a part of which is composed of a sectorand a shutter plate rotatably supported at one edge by a shaftpositioned at the center of said sector.

Other features of the operation of this invention will be described indetail hereinunder with reference to the accompanying drawings.

In the drawings: FIG. 1 is a cross-sectional view of an embodiment of asmoke damper according to this invention; and

FIG. 2 is a schematic diagram, partially in block form, representing thedamper of FIG. 1 and means for the operation thereof.

Throughout the drawings, like reference numerals are used to denotecorresponding structural components.

Referring to FIG. 1, the damper of this embodiment has an L-type casingl'consisting of a straight upright portion 11, a curved elbow portion 12and a straight horizontal portion 13. The upright portion 11 isconnected to a ventilation duct 2 and the horizontal portion 13 isconnected to a suction hood 3 positioned within an opening formed in thewall 4 of the building. The elbow portion 12 is a curved section havinga central angle 6 which is equal to 90 in the present embodiment. Ahorizontal rotating shaft 21 is supported at the center of the sector orcurved section of the elbow portion 12 and a flat shutter plate 20having a contour corresponding to the cross-section of the elbow portion1 is supported at one edge by the shaft 21. The shutter 'plate 20 isrotatable about the shaft-21 between the closed position 20 as shown andthe opened position 20' as shown in phantom. Thus, the shutter plate 20can completely close the elbow portion 12 with the central angle6. Aflow-rate control 30 having shutter wings 31 and a face grid 32 ispositioned in the suction hood 3. v 3

Referring to FIG. 2, the damper shaft 21 is coupled v through acrank-arm 22 to a piston rod 41 of an air cylinder having a piston 42which is always held in the lowermost postion by a spring 43. An airinlet port 44 attached to the bottom of the cylinder 40 is connectedthrough a hose 5 to an outlet port 51 of an electromagnetic air valve50. The air valve also has an air inlet port 52 connected through a hose6 to a compressed air source such as an air compressor (not shown) andan air exhaust port 53. The cylinder of the electromagnetic air valve50, includes an armature 55 which is actuated by an electromagnet 54 anda piston 56 is fixedly coupled through a connecting rod 57 to thearmature 55. The armature 55, piston 56 and respective ports 51, 52 and53 are arranged so that the ports 51 and 52 communicate when thearmature 55 is actuated and the ports 51 and 53 communicate when thearmature 55 is deactuated. The electromagnet 54 of the air valve 50 isconnected to a power source (not shown) through a main control switchboard 60 including a main switch 61 and a test switch 62, a localcontrol switch board including a thermostat switch 71 and a test switch72 and a fuse box including a fuse 81. The main control switch board 60is installed in the central control room and has a plurality of branchlines for feeding to the other dampers though they are omitted from thedrawing for the purpose of simplification. The local control switchboard 70 is installed near each damper and the fuse box 80 is installedin the damper casing 1.

When the main switch 61 is closed, the electromagnet 54 of the air valve50 is energized to pull up the armature 55 and of the piston 56. Thus,the ports 51 and 52 communicate to feed a compressed air to the aircylinder 40 through the hoses 6 and 5 from the compressed air source(not shown). The piston 42 is pushed up against the spring 43 to rotatethe crank arm 22, upwardly and maintain the shutter plate 20 of thedamper in the open position 20' (FIG. 1).

When the main switch 61 is opened manually in the case of fire,the'electromagnet 54 is de-energized and the piston 56 falls under itsown weight with the result that the ports 51 and 53 are placed incommunication. Accordingly, the air in the air cylinder 40 is exhaustedthrough the hose 5 and the port 53 and the piston 42 is pusheddownwardly by the spring 43 to rotate the shutter plate 20 to itscounterclockwise position to close the damper. The same damper closingaction also occurs in response to opening of the switches 62, 71 or 72or opening of the fuse 81 by excessive heat or other reason. Theoperation and objects of these switches are self-explanatory.

As previously described, the damper of this invention is fully closed aslong as the shutter plate 20 is within the central angle 0 of thesectorial or curved section of the elbow portion 12. A cam fixed to therotating shaft 21 of the shutter plate 20 is shaped so that it actuatesa switch 91 only when the shutter plate 20 is within the central angle0. The switch 91 is connected in an indicating lamp circuit (not shown)to indicate sufficient closure of the damper.

Although, in the above embodiment, the damper is connected to avertically extending ventilation duct and, therefore, the shutter plate20 of the damper is opened upwardly about the horizontal shaft 21, the

" spring force of the air cylinder 40, while, in the former case gravitysupplements the action of the spring.

As above described, the damper of this invention can sufficientlyintercept smoke and flame even if some deviation takes place in theposition of the closed shutter plate and, therefore, exhibits a highdegree of safety and reliability over the prior art dampers.

It should be noted that the above description has been made inconjunction with the illustrated embodiment only and various changes andmodifications may be made without departing from the scope of theinvention as defined in the appended claim.

I claim:

1. A fireproof smoke damper assembly comprising a duct having asubstantially straight section and a curved elbow section joined one tothe other, said curved section having a longitudinal section in the formof a sector of a circle having its center at one side of said duct, ashaft on said one side of said duct and substantially coincident withsaid center and a damper plate attached along one edge to said shaft forrotation within said duct about said center, said damper being movablefrom an open position lying against a wall of said straight section toclosed positions when disposed at any point within said curved sectionand is in close proximity with the wall of said curved section.

2. A fireproof smoke damper according to claim 1 including an armcarried by said shaft, a cylinder including a spring loaded piston, arod coupling said arm to said piston whereby said piston under theaction of said spring will normally hold said damper in the closedposition, means including an electrically operated valve for feeding afluid under pressure to said cylinder, said valve upon being energizedpermitting fluid pressure to act on said position and move it inopposition to said spring to open said damper and means on said valvefor interrupting said fluid pressure upon de-energization and permitdischarge of said fluid in said cylinder and said piston to move saiddamper to the closed position.

3. A fireproof smoke damperaccording to claim 2 including a powerswitch, a thermostatically controlled switch and at least one testswitch connected in series one with the others and with saidelectrically operated valve for controlling the application of energy tosaid valve.

4. A fireproof smoke damper according to claim 3 wherein a heatresponsive fuse is positioned within said damper casing and connected inseries with said switches.

1. A fireproof smoke damper assembly comprising a duct having asubstantially straight section and a curved elbow section joined one tothe other, said curved section having a longitudinal section in the formof a sector of a circle having its center at one side of said duct, ashaft on said one side of said duct and substantially coincident withsaid center and a damper plate attached along one edge to said shaft forrotation within said duct about said center, said damper being movablefrom an open position lying against a wall of said straight section toclosed positions when disposed at any point within said curved sectionand is in close proximity with the wall of said curved section.
 2. Afireproof smoke damper according to claim 1 including an arm carried bysaid shaft, a cylinder including a spring loaded piston, a rod couplingsaid arm to said piston whereby said piston under the action of saidspring will normally hold said damper in the closed position, meansincluding an electrically operated valve for feeding a fluid underpressure to said cylinder, said valve upon being energized permittingfluid pressure to act on said position and move it in opposition to saidspring to open said damper and means on said valve for interrupting saidfluid pressure upon de-energization and permit discharge of said fluidin said cylinder and said piston to move said damper to the closedposition.
 3. A fireproof smoke damper according to claim 2 including apower switch, a thermostatically controlled switch and at least one testswitch connected in series one with the others and with saidelectrically operated valve for controlling the application of energy tosaid valve.
 4. A fireproof smoke damper according to claim 3 wherein aheat responsive fuse is positioned within said damper casing andconnected in series with said switches.